Abstract : The standards and guidelines for avian species are based on the suggestions of the Institute of Laboratory Animal Resources stated as follows: To promulgate scientific standards of definition, terminology, and tolerable variability in regard to genetic constitution, nutrition, freedom from disease, housing conditions and maintenance for the major groups of animals in use. The report is concerned primarily with chickens. Since standards for production are readily available and are generally used by producers of chickens, primary emphasis has been placed on standards for laboratory users of this species. The White Leghorn has been used as a basis for developing the requirements, as this is the breed most commonly used by laboratory workers. Recommendations for all ages of chickens, fertile eggs, and started embryos are included.